Wing profile sail

ABSTRACT

A wing profile sail for sailboats and sailboards, formed by a flexible sheet having a leading edge configured to be coupled to a mast, includes inflatable bladder means extending along the direction of the leading edge, rearward thereto, to provide a wind profile to the sail. The inflatable bladder means includes multiple pockets fixed to the opposite surfaces of the flexible sheet and localized behind its leading edge.

FIELD OF INVENTION

The present invention is related to a sail for sailboats and sailboards, formed by a flexible sheet having a leading edge configured to be coupled to a mast, and provided with inflatable bladder means extending along the direction of the leading edge, rearwardly thereto, in order to provide a wing profile to the sail.

STATE OF THE PRIOR ART

From Italian patent IT-1353528B such a sail is known having a tubular inflatable portion with an aerodynamic profile having a variable section, maximum in substantial correspondence of a generally central area of the leading edge or an area of larger sail surface, and minimum in correspondence of the ends of the leading edge or of areas of smaller sail surface. This arrangement enables improving the aerodynamic performance at the transition area between the mast and the sail, thus enhancing its efficiency. From the manufacturing viewpoint, this solution contemplates providing the sail with an inflatable tubular portion either directly, or with the aid of resilient air chambers housed within such a tubular portion, which evidently requires manufacturing techniques which need to be different and more complex as compared with those of the traditional sails.

Similar drawbacks are affecting the wing profile sails having inflatable bladder means as disclosed in documents U.S. Pat. No. 5,347,946, GB1153056, U.S. Pat. No. 3,391,668, US-2002/0100406 e U.S. Pat. No. 5,775,249, all of which are providing for the whole sail a double or triple wall arrangement and in some instances fitting inflatable bladders therein.

Namely, in the case of the wing profile sail disclosed and illustrated in document US-2002/0100406A the inflatable bladders are housed within hollow spaces formed between an inner flexible sheet and two flexible outer sheets extending rearwardly along the entire width of the inner sheet, and also forming an outer shell surrounding forwardly the mast. This arrangement involves a number of drawbacks: firstly it cannot be directly applied to a conventional sail consisting of a single flexible sheet, but requires instead a complex sail construction formed by an inner flexible sheet, necessarily provided with transverse battens, and by an outer shell. Secondly, it does neither allow any adjustments of the maximum thickness of the aerodynamic profile, nor it can even be employed with traditional masts since it necessarily requires that the mast be able to rotate around its axis so as to provide the desired aerodynamic wing profile to the leading edge of the sail. Moreover the battens of which the inner sheet is equipped need to be coupled forwardly to the rotatable must to transfer the necessary tension to the wing so as to maintain its aerodynamic profile, which further complicates the structure formed by the sail and mast assembly. Lastly, in order to avoid that the inflatable bladders may shift randomly inside the hollow spaces between the inner sheet and the outer shell, thus negatively affecting the aerodynamic profile, flexible retainer flaps are provided which connect individually in a loose fashion each bladder with the inner sheet and which, besides not ensuring proper maintenance of the optimum aerodynamic profile, involve additional noticeable constructive complications.

Also in the case of document U.S. Pat. No. 5,775,249 the inflatable profile is obtained by means of complex structure composed by two parts: a leading edge portion fixed around the mast and consisting of two inflatable cells enclosed within a partially semi-non-elastic and partially rigid outer cover, and a main body portion in turn containing two inflatable cells enclosed within an outer cover made of elastic material and extending for the entire width of the sail as far as its trailing edge. In addition to a constructive complexity, neither this solution enables adjusting the position of the maximum thickness of the aerodynamic profile with respect to the mast. Moreover, the presence of the rigid part of the leading edge portion prevents applying this solution to conventional masts provided with crosstrees for rigging.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the above-mentioned drawbacks, and more particularly to provide a wing profile sail enabling to maintain unchanged the general construction of the traditional sails, thus implementing the wing profile with a simple and relatively economical arrangement.

A further object of the invention is to provide a wing sail whose profile thickness can be easily adjusted so as to achieve an enhanced efficiency in terms of greater lift, even at low angles of incidence of the wind, i.e. even at close-hauled sailing of the boat equipped with the sail according to the invention.

A further object of the invention is to enable achieving those advantageous effects even by means of a simple and relatively unexpensive modification of already existing sails even already in use.

According to the invention these objects are obtained by virtue of a wing profile sail of a type set forth in the preamble of claim 1, whose primary characteristic resides in that the inflatable bladder means are fixedly secured to the opposite surfaces of the flexible sheet.

The inflatable bladder means conveniently include two groups of multiple side-by-side, flexible and substantially inextensible pockets localized immediately behind the leading edge of the sail so as to conveniently occupy about ½ of its width.

The multiple pockets can be inflatable directly, or inflatable resilient tubular bladders can be housed within the pockets.

The pockets have advantageously a differentiated width, smaller in correspondence of the proximal and distal ends of each group and greater in correspondence of the intermediate areas.

Moreover the pockets have preferably a progressively increasing width towards the area of the maximum chord of the wing surface, i.e. towards the foot of the sail.

According to a preferred embodiment of the invention, each group of multiple pockets is formed by a prefabricated mat, designed to be firmly applied to a respective surface of the sheet either permanently or in a detachable fashion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be disclosed in detail with reference to the accompanying drawings, purely provided by way of non limiting example, in which:

FIG. 1 is a diagrammatic and partially broken perspective view of a wing sail according to the invention, coupled to the mast of a boat,

FIG. 2 is a lateral elevational view of FIG. 1,

FIG. 3 shows a variant of FIG. 1,

FIG. 4 is a horizontally sectioned view in a larger scale along line IV-IV of FIG. 1,

FIG. 5 is a partial enlargement of FIG. 4,

FIG. 6 is a horizontally sectioned view along line IV-IV of FIG. 3,

FIG. 7 shows a variant of FIG. 6 in an enlarged scale;

FIG. 8 is an elevational diagrammatic view of a pre-fabricated construction of one of the inflatable pockets of a sail according to the invention,

FIG. 9 is a perspective view from below of FIG. 8,

FIG. 10 is a perspective view from above of FIG. 8,

FIG. 11 is a top plan view showing diagrammatically the application of each pre-fabricated group of inflatable pockets according to FIGS. 8-10 to the sail,

FIG. 12 is a view similar to FIG. 11 which shows diagrammatically the application of each pre-fabricated group of inflatable pockets according to FIGS. 4 and 5 to the sail,

FIGS. 13 and 14 show two variants of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

The wing profile sail according to the invention consists of a usual and conventional mainsail formed by traditional techniques as a single flexible sheet typically made by cloth, mylar® , dacron® or similar materials, whose leading edge or luff is provided in a way also known per se with slides 3 or similar conventional systems for coupling thereof for instance to the hoist of the vertical mast 4 of a sailboat. The mast 4, whose cross section is for instance the one depicted in FIGS. 4, 6 and 7, is also of a conventional type and is normally stationary, i.e. non rotatable.

In order to provide a wing profile to the sail 1, by means of which the lift and thus the efficiency of the sail are appreciably enhanced, the invention consists of applying an inflatable bladder system conveniently localized immediately behind its leading edge 2, along at least ½ of the width of the sheet 1, without requiring any modifications of the usual conformation of the sail beside such an addition.

As it is better visible in FIGS. 4 and 5 the inflatable system, generally designated as 5, occupies for instance ½ of the width of the sail 1 and comprises two groups 6, 7 of multiple pockets (four in the shown example) 6 a, 6 b, 6 c, 6 d and 7 a, 7 b, 7 c, 7 d, which are flexible and generally inextensible. Each group 6, 7, which as it will be pointed out in the following is conveniently pre-fabricated, is directly and firmly fixed on a respective surface of the sheet 1, in a permanent or, preferably, in a detachable fashion.

In the case of the example here disclosed the multiple pockets 6 a, 6 b, 6 c, 6 d and 7 a, 7 b, 7 c, 7 d are to say so built on the sheet 1: they are delimited by the opposite faces 1 a, 1 b, of the sheet 1, by respective flexible transverse baffles 8 projecting outwardly from the faces 1 a, 1 b, and by respective outer flexible walls 9, 10 generally parallel to the faces 1 a, 1 b and possibly in part of totally elastic.

The transverse baffles 8 are fixedly secured to the faces 1 a, 1 b of the sheet 1 for instance by sewing. According to a variant, shown in FIG. 6, the transverse baffles 8 can be mutually joined by, or formed in one piece with, respective inner flexible walls 8 a, fixed to the faces 1 a, 1 b of the sheet 1. Thus the pockets 6 a, 6 b, 6 c, 6 d and 7 a, 7 b, 7 c, 7 d present, along with the outer flexible walls 9, 10, a tubular configuration. According to a further variant, which will be disclosed in the following and is presently considered as the preferred embodiment of the invention, each group of multiple pockets 6 a, 6 b, 6 c, 6 d and 7 a, 7 b, 7 c, 7 d is pre-fabricated and then applied to the respective surfaces 1 a, 1 b of sheet 2, even in a releasable way.

As it is evident from FIGS. 4 and 5, the pockets 6 a, 7 a arranged in correspondence of the proximal end (i.e. the one adjacent to the leading edge 2)of each group 6, 7, as well as the pockets 6 d, 7 d located in correspondence of the distal end (i.e. the one which is far away from the leading edge 2) of those groups 6, 7 have a lesser width (as measured transversally of the sail) than the width of the intermediate pockets 6 b, 6 c and 7 b, 7 c. Typically the pockets having the maximum width are the pockets 6 b, 7 b located at about ⅓ or less of the total width of the groups 6, 7, towards the side of the leading edge 2: this configures the inflatable system 5 essentially as a NACA profile.

As it can be partially seen in FIG. 1 and in FIG. 2, the two groups 6, 7 may start superiorly from a certain distance from the top or head 1 c of the sail and are extending inferiorly down to a certain distance from its foot 1 d which is usually designed (in the case of a sailboat) to be coupled to a boom. Moreover the width of the pockets 6 a-6 d and 7 a-7 d (measured parallelly to the sail) is progressively increasing towards the clew 1 d, which in this case normally corresponds to the area of maximum chord of the sail surface.

In the embodiment here disclosed, within each one of the pockets 6 a-6 d and 7 a-7 d, which are closed at the respective upper and lower ends, a respective inflatable bladder is housed which is consisting of an elastic tubular element 11, typically having a thin wall for instance of the type employed in inflatable traction kytes.

The bladders 11 are connected, for instance inferiorly and through respective valves not shown since within the skill of the practitioner, to an inflating device in turn controlled so as to supply air under pressure to the bladders 11 jointly or independently from one other, in a selective and differentiated fashion or even in a combined way, according to logics intended to adjust the aerodynamic conformation of the wing profile of the inflatable system 5 in the transition area between the mast 4 and the leading edge 2, and immediately behind the latter. This enables to achieve an increased global efficiency of the sail 1 as a function of the different angles of incidence of the wind and thus for the different sailing points of the sailboat fitted out with the sail itself.

Theoretical calculations and experimental tests which are being presently carried out by the applicants demonstrated that the configuration now considered as the preferred one is that shown in FIG. 4 in which under equilibrium conditions, i.e. without any wind pressure on either surface 1 a, 1 b of the sail 1, the inflatable system 5 has a maximum width at the area of the pockets 6 b, 7 b which, as stated, are arranged at about ⅓ of the total width of the inflatable system 5, towards its proximal end. This maximum width is greater than the width, i.e. of the cross section, of the mast 4.

This area of maximum width can be advantageously shifted forwardly or rearwardly, evidently acting on the pressure of the air supplied to the bladders 11, in the way which is deemed most proper to further increase the efficiency of the sail for each sailing point.

In order to make the outer surfaces of the two groups of pockets 6, 7 as smooth as possible, the related flexible walls 9, 10 can be partially or totally covered and enclosed by respective flexible joining panels 14, 15 extending, starting from the leading edge 2, as far as the surfaces 1 a, 1 b of the sail 1, for instance beyond half or more of its extension, or which may simply connect the surfaces of maximum width of the pockets 6 and 7 to one another.

Preferably, however not necessarily, each flexible panel 14, 15, or each rear pocket 6 d and 7 d, can be connected to the surfaces 1 a, 1 b of the sail 1 by means of a respective elastic portion 14 a, 15 a, for instance made of Lycra® . As an alternative the flexible panels 14 and 15, when provided, can be entirely elastic.

A first variant of the invention is shown in FIGS. 3 and 6 (in which parts which are identical or similar to those already previously disclosed are designated by the same numeral references) and enables to further improve the aerodynamic flow in the transition area between the mast 4 and the leading edge 2 of the sail 1, making it as undisturbed as possible. This variant consists of the provision of two flexible baffles designated as 16, 17 in FIG. 6, which connect the front surface of the mast 4 with the inflatable system 5 on the side 1 a and on the side 1 b of the sail 1, respectively.

The variant of the invention depicted in FIG. 7 differs from the embodiment of FIG. 6 in that the two flexible baffles 16, 17 are fixed on one side to the surfaces 1 a, 1 b of the sheet 1 and on the opposite side to the mast 4 through a rope or cable system 18, 19 designed to provide the tension which is necessary to warrant adherence between the surface of the mast 4 and the baffles 16, 17 during operation, and suitable to allow fitting out of the sail. To such effect the ropes 18, 19 are wound around respective sheeves (not shown in the drawings) provided on the masthead, one at each side.

As previously pointed out, according to one embodiment which is presently considered as the preferred one each pocket group 6, 7 is conveniently formed in one piece as a prefabricated mat, such as shown as 21 in FIGS. 8-10 with reference to the group 6, which in this case is including six pockets 6 a-6 f.

The pockets 6 a-6 f, which are flexible and substantially inextensible, can be inflated directly, i.e. without employing the elastic bladders 11 of the embodiments previously disclosed. In this case each pocket 6 a-6 f is provided with one or more inflating valves, diagrammatically indicated as 22. Each pocket 6 a-6 f can also be divided longitudinally in separate compartments, each one provided with a respective inflating valve.

Each mat 21 is configured to be easily applied onto a respective surface 1 a, 1 b of the sheet 1 of any traditional sail, even already existing, in a permanent fashion for instance by gluing or heat welding, or more conveniently in a releasable fashion with the aid of micro-hook strips (Velcro®) or similar systems for quick attachment-detachment, in the way shown in FIG. 11. The mats 21 are not necessarily provided with the walls 9, 10, or with the flexible panels 14, 15, or with the baffles 16, 17 disclosed in the above.

FIG. 12 shows the permanent or releasable application of the pocket groups 6, 7 according to FIGS. 4 and 5 to the sheet 1 of the sail.

FIGS. 13 and 14 are showing two simplified variants of FIG. 5, deprived of the elastic tubular bladders 11: in either case the pockets 6 a-6 d and 7 a-7 b, mare of airtight material, are designated to be directly inflated and thus do constitute themselves the inflatable bladder means fixedly secured to the opposite faces 1 a, 1 b of the sheet 1 forming the sail. In the embodiment of FIG. 13 the flexible panels 14, 15 with the related rear elastic portions 14, 15 a are provided at the outside of the pockets 6 a-6 d and 7 a-7 d, while in the embodiment of FIG. 14 the flexible panels 14, 15 are suppressed and only the elastic portions 14 a, 15 a are provided, connecting the rear pockets 6 d and 7 d with the respective surfaces 1 a, 1 b of the sail 1.

Also in these variants the pockets 6, 7 are connected, for instance inferiorly and through respective valves not shown in the drawings, to an inflating device in term controlled so as to supply air under pressure to the pockets 6, 7 jointly, or independently in a selective and differentiated fashion, even variously combined, according to control logics adapted to adjust the aerodynamic conformation of the wing profile of the inflatable system 5. The position of the area of maximum width, as already previously explained, can be advanced or retracted with respect to the mast 4, by differentiating the pressure of the air supplied to the pockets 6, 7 according to any mode which shall be considered proper to optimize the efficiency of the sail at any different sailing points.

Naturally the details of construction and the embodiments can be widely vary with respect to what has been disclosed and illustrated, without thereby departing from the scope of the present invention such as defined in the appended claims. Thus, for example, the general design of the sail can be different from the one shown in the drawings, and be adapted for use with sailboards. 

1. A wing profile sail for sailboats and sailboards, formed by a flexible sheet having a leading edge configured to be coupled to a mast and comprising inflatable bladder means extending in a direction of said leading edge rearward thereto and arranged to provide a wing profile to the sail, wherein the inflatable bladder means are fixedly secured to the opposite surfaces of the flexible sheet.
 2. The sail according to claim 1, wherein said inflatable bladder means include two groups of multiple flexible pockets arranged side-by-side.
 3. The sail according to claim 2, wherein said multiple pockets are substantially inextensible.
 4. The sail according to claim 2, wherein said multiple pockets are directly inflatable.
 5. The sail according to claim 2, wherein said respective tubular inflatable resilient members are housed within said multiple pockets.
 6. The sail according to claim 2, wherein said pockets have a differentiated width.
 7. The sail according to claim 6, wherein said pockets have a smaller width at a proximal end and at a distal end of said two pocket groups and have a greater width in correspondence of intermediate zones of said two pocket groups.
 8. The sail according to claim 7, wherein said intermediate zones are located at a variable position in a range of ⅓ or less of the width of said two pocket groups starting from said leading edge.
 9. The sail according to claim 7, wherein a maximum width of said two pocket groups is greater than a transverse section of the mast.
 10. The sail according to claim 2, wherein said pockets have a progressively increasing width towards the foot of the sail.
 11. The sail according to claim 2, wherein said pockets terminate at a distance from a head and/or from a foot of the sail.
 12. The sail according to claim 2, wherein each pocket group is covered, on its side opposite to the respective surface of the sheet, by at least one flexible panel generally parallel to said sheet.
 13. The sail according to claim 12, further comprising two additional flexible joining panels enclosing said two pocket groups and extending from said leading edge as far as an area of said sheet located rearward to said two pocket groups.
 14. Sail The sail according to claim 13, wherein said two additional flexible joining panels are at least in part elastic.
 15. The sail according to claim 13, wherein said area is located in correspondence of at least half width of the sheet.
 16. The sail according to claim 2, further comprising two flexible baffles designed to join said two pocket groups to the front surface of the mast at opposite sides of said leading edge.
 17. The sail according to claim 2, wherein each group of multiple pockets is formed as a prefabricated mat.
 18. The sail according to claim 17, wherein each prefabricated mat is designed to be applied onto the respective surface of the sheet in a releasable fashion.
 19. The sail according to claim 1, wherein said inflatable bladder means are configured to be inflated according to a joint or independent and selective or combined mode.
 20. The sail according to claim 1, wherein said leading edge is designed to be connected to the mast through a single or a multiple connecting system.
 21. The sail according to claim 1, wherein said inflatable bladder means are localized immediately behind said leading edge and extend substantially for ½ or less of the width of the sheet. 